The present invention relates, in general, to the field of differential amplifiers. More particularly, the present invention relates to a differential amplifier circuit of especial applicability to low voltage operations and a bias technique for enabling the accommodation of an increased range of input levels.
Differential amplifiers are utilized to amplify, and produce an output signal which is a function of the difference between two differential, or complementary, input signals and to thereby enable the detection of relatively weak signal levels while inherently rejecting noise common on the differential input lines. In this regard, conventional integrated circuit differential amplifier designs have included the provision of a differential pair of input transistors having a current mirror load and which are also coupled to a current source for providing a single output signal in response. However, as transistor dimensions and power supply levels tend to decrease, the ideal operational characteristics of such conventional circuit designs cannot be achieved and the functionality of the circuit becomes increasingly dependent on transistor parameters, temperature and operating voltages to a highly significant degree.